How can I stop caring about what my parents think?

This is rather embarrassing considering my age. I still live with my parents (don't judge please, I don't live in the US, and here the age you become independent is a bit older).

I'm in a new relationship. I'm very happy and all, but I fear my parents judging me or whatever... actually, I think my mom is happy and all, but my dad has always been a bit, well, "too much of a dad" when it comes to guys, also I'm his youngest daughter.

Last night for example, we had a family gathering, and for a while I was just talking to my boyfriend and he caressed my face and I kissed him, and my father told me (in private, of course) that I should "tone it down". Seriously, it wasn't all too sexual or too intimate or whatever as to make people uncomfortable, at least I didn't think so, so it sucked.

I want to move out, but until I do, I'll have to deal with this. I hate going to my boyfriend's for the same reason, because even though it's obvious I'm not a child anymore and it's obvious that we must have sex when I go... I just hate how stern my dad gets when I tell him where I'm going, or that he and mom think I'm a slut.

With my ex it was the same... and I guess in a way they judge me more harshly than they judge my sister, because my ex was a serious d-bag. But I don't know, I've always been more of a party girl and such than my sister, so I've always felt they judge me. They never tell me to my face, but it's their attitude, and sometimes they make some comments to my sister and she tells me.

I feel so hurt and uncomfortable by all that. I'm old, I'm an adult, and I know I shouldn't care but I do... until I move out, I'l have to deal with it, though. But how?